/*
  * Mirante Tecnologia
  * Copyright 2010, Mirante Informatica LTDA, 
  * and individual contributors as indicated by the @authors tag
  *
  * This is free software; you can redistribute it and/or modify it
  * under the terms of the GNU Lesser General Public License as
  * published by the Free Software Foundation; either version 2.1 of
  * the License, or (at your option) any later version.
  *
  * This software is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this software; if not, write to the Free
  * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
  */
package com.miranteinfo.seam.hibernate.usertype;

import java.io.Serializable;
import java.lang.reflect.Method;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

import org.hibernate.HibernateException;
import org.hibernate.type.NullableType;
import org.hibernate.type.TypeFactory;
import org.hibernate.usertype.ParameterizedType;
import org.hibernate.usertype.UserType;

/**
 * Implements a generic enum user type identified by a single identifier / column.
 * <p><ul>
 *    <li>The enum type being represented by the certain user type must be set
 *        by using the 'enumClass' property.</li>
 *    <li>The identifier representing a enum value is retrieved by the identifierMethod.
 *        The name of the identifier method can be specified by the 
 *        'identifierMethod' property and its default is the name() method ('name').</li>
 *    <li>The identifier type is automatically determined by 
 *        the type of the identifierMethod.</li>
 *    <li>The valueOfMethod is the name of the static factory method returning
 *        a enumeration object represented by a given indentifier. The valueOfMethod's
 *        name can be specified by setting the 'valueOfMethod' property. The
 *        default valueOfMethod's name is 'valueOf'.</li>
 * </p> 
 * <p>
 * Example of a enum type represented by an int value:
 * <code>
 * public enum SimpleNumber {
 *   Unknown(-1), Zero(0), One(1), Two(2), Three(3);
 * 
 *   public int toInt() { return value; }
 *   public SimpleNumber fromInt(int value) {
 * 		switch(value) {
 *   	   case 0: return Zero;
 *         case 1: return One;
 *         case 2: return Two;
 *         case 3: return Three;
 *         default:
 *         		return Unknown;
 *     }
 *   }
 * }
 * </code>
 * <p>
 * The Mapping would look like this:
 * <code>
 *    <typedef name="SimpleNumber" class="GenericEnumUserType">
 *		<param name="enumClass">SimpleNumber</param>
 *		<param name="identifierMethod">toInt</param>
 *		<param name="valueOfMethod">fromInt</param>
 *    </typedef>
 *    <class ...>
 *      ...
 *     <property name="number" column="number" type="SimpleNumber"/>
 *    </class>
 * </code>
 * 
 * @author Martin Kersten
 * @since 05.05.2005
 * 
 * @author lucas lins
 */
@SuppressWarnings("unchecked")
public class GenericEnumUserType implements UserType, ParameterizedType {
	private static final String DEFAULT_IDENTIFIER_METHOD_NAME = "name";
	private static final String DEFAULT_VALUE_OF_METHOD_NAME = "valueOf";
	
	private Class<? extends Enum> enumClass;
	private Class<?> identifierType;
	private Method identifierMethod;
	private Method valueOfMethod;
	private NullableType type;
	private int[] sqlTypes;

	public void setParameterValues(Properties parameters) {
		String enumClassName = parameters.getProperty("enumClassName");
		try {
			enumClass = Class.forName(enumClassName).asSubclass(Enum.class);
		} catch (ClassNotFoundException cfne) {
			throw new HibernateException("Enum class not found", cfne);
		}

		String identifierMethodName = parameters.getProperty("identifierMethod", DEFAULT_IDENTIFIER_METHOD_NAME);

		try {
			identifierMethod = enumClass.getMethod(identifierMethodName, new Class[0]);
			identifierType = identifierMethod.getReturnType();
		} catch (Exception e) {
			throw new HibernateException("Failed to obtain identifier method", e);
		}

		type = (NullableType) TypeFactory.basic(identifierType.getName());

		if (type == null)
			throw new HibernateException("Unsupported identifier type " + identifierType.getName());

		sqlTypes = new int[] { type.sqlType() };

		String valueOfMethodName = parameters.getProperty("valueOfMethod", DEFAULT_VALUE_OF_METHOD_NAME);

		try {
			valueOfMethod = enumClass.getMethod(valueOfMethodName, new Class[] { identifierType });
		} catch (Exception e) {
			throw new HibernateException("Failed to obtain valueOf method", e);
		}
	}

	public Class returnedClass() {
		return enumClass;
	}

	public Object nullSafeGet(ResultSet rs, String[] names, Object owner) throws HibernateException, SQLException {
		Object identifier = type.get(rs, names[0]);
		if (identifier == null) {
			return null;
		}

		try {
			return valueOfMethod.invoke(enumClass, new Object[] { identifier });
		} catch (Exception e) {
			throw new HibernateException("Exception while invoking valueOf method '" + valueOfMethod.getName() + "' of " + "enumeration class '"
					+ enumClass + "'", e);
		}
	}

	public void nullSafeSet(PreparedStatement st, Object value, int index) throws HibernateException, SQLException {
		try {
			if (value == null) {
				st.setNull(index, type.sqlType());
			} else {
				Object identifier = identifierMethod.invoke(value, new Object[0]);
				type.set(st, identifier, index);
			}
		} catch (Exception e) {
			throw new HibernateException("Exception while invoking identifierMethod '" + identifierMethod.getName() + "' of " + "enumeration class '"
					+ enumClass + "'", e);
		}
	}

	public int[] sqlTypes() {
		return sqlTypes;
	}

	public Object assemble(Serializable cached, Object owner) throws HibernateException {
		return cached;
	}

	public Object deepCopy(Object value) throws HibernateException {
		return value;
	}

	public Serializable disassemble(Object value) throws HibernateException {
		return (Serializable) value;
	}

	public boolean equals(Object x, Object y) throws HibernateException {
		return x == y;
	}

	public int hashCode(Object x) throws HibernateException {
		return x.hashCode();
	}

	public boolean isMutable() {
		return false;
	}

	public Object replace(Object original, Object target, Object owner) throws HibernateException {
		return original;
	}
}